Services you should be using: CloudSponge contacts importer
http://www.cloudsponge.com/
Previously I've used OpenInviter to import user contacts, but it tends to break and remains broken for months. I've switched to CloudSponge and now everyone's happy.
- Works with the 4 major webmail services plus Outlook and Mac Address Book
- Very simple to integrate
- Looks good out of the box, but can be customized
- You can choose to use their API directly for full control
Pricing is $25 per month (first month is free).
Disclaimer: I'm not associated with CloudSponge in any way, just a fan.
Thanks for the shout out ishi.
I'm the Founder of CloudSponge, if any HN people have questions just drop me a line.